Photoelectric device for measuring light output values in photo-printing machines



Sept. 24, 1963 M. w. KLAUSNER 3,105,107

PHoToELEcTRIc DEVICE EUR MEASURING LIGHT OUTPUT vALUEs IN PHOTO-PRINTING MACHINES Filed June 5, 1958 United States Patent O PHTGELECTRIC DEVICE FDR MEASURING LIGHT UUTPUT VALUES IN PHTO-PRHQ'IING MACHINES Melvin W. Klausner, North Bergen, NJ., assigner to Engelhard Hanovia, Inc., a corporation of New Jersey Filed June 3, 1958, Ser. No. '739,507

1 Claim. (Cl. 88-23) Thev present invention deals with a measurement device for photo-printin'gmachines and more particularly with a device for measuring light output values of lamps employed in photoprinting machines.

In photo-printing machines designed for the exposure of engineering reproduction materials, such as positive Working diazo type papers, both dry and moist developing, the material to be exposed is positioned, together with the drawing ortracingl to be copied, on a moving endless lbelt or a plurality of belts and fed over a rotatable drum or rotating glass cylinder, or a convex cylindrical surface of a transparent glass sheet, or semi-tubular member, or the like, and exposure is effected by means of a light source positioned-therein. The endless belt or belts move over a series of rollers and convey the tracing and light sensitive material over the cylindrical surface. During exposure, the belt or belts hold the printing material in contact with the cylindrical transparent surface while passing thereover.

The light source for the photo-machines is in the form of an elongated tube for emitting high intensity ultra violet radiations.

While the lamp registers an even light intensity under laboratory test conditions prior to assembly in the machine, it may give an uneven output under actual operating conditions as a result of electrical imperfections in the machine itself, a dirty drum, or some mechanical interception to the emitted light.

It is extremely diicult to measure the light output of the lamp under photo-machine operating conditions without dismounting the lamp.

One method of testing light output is -to pass and expose `a strip of photo-sensitive printing paper through the machine at both ends and the center of the rotating drum and to observe if any difference in shading occurs among the exposed strips. It is extremely difficult to visually ascertain shading differences Within a degree of desirable accuracy. Consequently, the machine may be unnecessarily operating below peak eiciency.

It is an. object of the present invention to provide a device for measuring the light output of photo-printing lamps under operating conditions. It is another object of the invention to provide a device for measuring light output of photo-printing machines without dismounting the source of light. It is another object of the present invention to provide a device for electrically measuring the light output of a photo-printing lamp during operation of the photo-printing machine. Other objects and advantages of the invention will become apparent from the description hereinafter following and the drawings forming apart hereof, in which:

FIGURE 1 is a cross sectional and schematic view of a conventional photo-printing machine including conveyor belts and ya light source,

FIGURE 2 is a front view of FIGURE l along lines 2-2 of FIGURE l,

FIGURE 3 is a top plan view of a measuring device according to the invention for measuring the light output of a photo-printing machine,

FIGURE 4 is an enlarged cross-sectional view along lines 4 4 of FIGURE 3,

FIGURE 5 is atop View of a modification of the device according to the present invention, Vand FIGURE 6 is a cross-sectional view of another modification according to the invention.

The invention deals with a device for measuring the light output of photo-printinglamps during actual operation of the photo-printing machine incorporating the lamps, whereby a strip member having a photocell sensing member and conductor means therefor is passed through the machine in exposed relationship to the light radiation.

FIGURES 1 and 2 illustrate a conventional photo-printing machine system and associated members, including a source of light 1 Within a transparent cylinder 2. An endless belt system 3 is moved over rollers 4, 5, 6, 7, at least one of which may be driven by a driving means. The rollers are arranged to permit the belt system 3 to engage the convex surface of the cylinder 2, which, for example, 'is mounted for rotation about the source of light. A measuring device 8, hereinafter more particularly described and including a photocell member 9, is fed around the convex cylindrical surface of cylinder 2. for exposure of photocell member 9 to the said light source, said belt system pressing the device S against the convex surface t during passage thereover.

The belt system is composed of a plurality of parallel belts R with spacings S therebetween.

The invention relates to a measuring device applicable for the measurement of light output of a lamp mounted in a photo-printing machine such as illustrated by FIG- URES 1 and 2, the measuring device being illustrated by FIGURES 3 to 6i.

Referring to FIGURES 3 and 4, the device comprises a longitudinal sheet or strip 8 having a light sensitive unit 9 aiXed thereto, preferably at an end portion thereof, and electrical conductors 1li and 11 connected to the light sensitive unit and extending longitudinally of the strip 8. The `sheet or strip 8 is composed of a flexible material, preferably a light transmissve plastic material, and the light sensitive unit 9 is a substantial conventional type photocell capable of transforming light into electrical energy. n

`For example, the photocell comprises a base metal layer 12., such as aluminum, bonded to a llayer of light sensitive metal 13, preferably selenium, the conductor 10 being electrically connected to the base metal layer and the conductor 11 being connected to the selenium layer. The layer of selenium may be coated on a thin base metal, such as aluminum, iron, nickel, etc., by vacuum evaporation or pasting and subsequently heat treated. The conductors 16' and 111, positioned longitudinally of the strip 8, are connected to an electrical indicating means or ammeter 14. The strip 8 is provided with indicia 15 spaced from each other longitudinally of the strip. FIGURE 5 illustrates a modification of FIGURE y-l wherein a plurall ity or bank of photocells 16 are spaced longitudinally of vstrip 3 and connected in parallel to conductors 17 and 18. The ban-k of photocells 16 may be connected in electrical series instead of in parallel electrical ,arrangement with functional equivalency. The photocell 9 and photocells 1d are connected to ammeter 14.

FIGURE 6 shows another modification of the invention similar to that of FIGURE 4 as to like components, except that the photocell components 12` land 13 and conduotors lil and 11 are imbedded in a light transmissive flexible plastic strip 19. The ends of the conductors lo and 1:1 extend outwardly of the strip asV illustrated by FIGURE 3. The plurality of photo-cells 9 and 16 and conductors 10, 11, 17 and 1S may be also imbedded in a plastic strip similar to that illustrated by FIGURE 6-.

In operation the flexible strip S of FIGURE 3, having a photocell 9 and conductors lil and 11 mounted thereon and with the conductors connected to ammeter 14, is inserted into the photo machine with the photocell passing between the cylindrical tube and belt system 3 of FIG- Y illustrated, various modifications are contemplated URES 1 and 2. As theV photocell passes around the cylinder tube, periodic readings of photocell response, atV

the standard indicatesy that the lamp l is not operating at peak eiciency. 4 Y Y When.` themeasuring device according to FIGURE 5 is employed, and with Ithe switch 21 open, the'device operates similarly Ito that of FIGURE 3. y switch 21 is closed, andrbecause the photoce-lls 16 are connectedto the ammeter14 by means of conductors 17 and 1-8, the response of eachvphotocell is collectively additive and the reading of the ammeter is' yan automatic average reading. Should the average reading deviate from a standard comparison value, the lamp is operating below peak eiliciency and corrective measures are indil cated. Y

. The ammeter 14V may be replaced by an electrical output recording apparatus to Vprovide arrecord of the cell response for future referenceyagainst which subsequent readings are maken to determine decline of lamp eiiiciency withruse., Y Y

While'the'invention has been specifically described and Within the scope of the appended claim.

However, when c Y 4 What isclaimed is: A light responsive measuring device comprising a thin elongated flexible light lrransmissive sheet, Ia thin photo- Y electric member affixed to `and localized vat one end portion of the sheet, electrical conductor means connected to the photoelectric Vmember and positioned longitudinally of the sheet I'and extending from the photoelectric member at the said one end portion Yof the sheet toward the other end thereof, land a photoelectric response measuringme-ans electrically connected to the conductor means. i

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